In the past, various and sundry methods were employed to treat the windings of a dynamoelectric machine core, such as a stator or a rotor core for instance, and in some instances also the core itself, with a hardenable or curable liquid adhesive material. For instance, one typical past stator or core had laminations fixedly interconnected in a stack thereof by suitable means, such as welding, bonding, or cleating or the like for instance, and winding means associated with the stator included a plurality of coils having opposite side turn portions received in slots provided therefor in the stator and opposite end turn portions arranged in generally annular groupings thereof adjacent the opposite end faces of the stator. Of course, suitable insulation, such as slot liners or the like for instance, were provided in the stator slots to electrically insulate the opposite side turn portions of the coils from the stator, and suitable winding retaining means, such as slot wedges or the like for instance, were positioned in the stator slots to maintain the opposite side turn portions of the coils against displacement therefrom into the bore of the stator core. In some instances, the opposite end turn portions of the coils were laced or tied with twine in a manner well known to the art. Also in some instances, an insulating sleeve of a suitable material was placed over the lead ends of the winding means which emanated from various slots of the stator adjacent an opposite end face thereof.
In one of the past methods of treating the winding means associated with the above discussed past stator when the laminations thereof were fixedly interconnected together, such as by welding or cleating for instance as previously mentioned, the stator and winding means were baked or preheated to a preselected temperature sufficient to at least preanneal the winding means, and while at such an elevated temperature, the stator core and winding means were fully submersed or dipped into a bath of the liquid adhesive material. When later removed from the liquid adhesive material bath, the stator and winding means were transferred to a curing oven to be rebaked or reheated to effect the curing of the liquid adhesive material which had adhered to the stator core and winding means. In some instances, the stator and winding means may have been further redipped and rebaked. Of course, while the cured liquid adhesive material on the opposite end turn portions of the coils may have added some degree of rigidity thereto, it is believed that one of the disadvantageous or undesirable features of such past treatment method was that the stator slots may not have been adequately filled with the liquid adhesive material during the dipping of the stator so that the opposite side turn portions of the coils within the stator slots may not have been adequately saturated or encapsulated by the liquid adhesive material when cured. As a result, it is believed that the strength of the winding means in the stator may have been impaired and also that the opposite side turn portions of the coils may not have been rigidly contained within the stator slots. Further, it is also believed that another disadvantageous or undesirable feature of the past treatment method may have involved the loss, such as by dripping or the like for instance, of liquid adhesive material from the winding means during the transfer of the stator and winding means from the liquid adhesive material bath to a curing oven for baking, and it is also believed that such loss of liquid adhesive material may have created voids between the interstices of at least the opposite end turn portions of the coils serving to weaken them. Thus, it is also believed that when the winding means were energized in a dynamoelectric machine, the opposite end turn portions and opposite side turn portions of the coils may have been movable in response to such energization to an extent wherein the insulation thereon was worn or rubbed away causing short circuits in such winding means. Still another disadvantageous or undesirable feature of the past treatment method is believed to be that it may have been necessary to wipe excess liquid adhesive material from the opposite end faces and the peripheral or circumferential surface therebetween of the stator core prior to baking the stator and winding means to cure the liquid adhesive material thereon. A still further disadvantageous or undesirable feature of the past treatment method is believed to be that the insulating sleeves on the lead ends of the winding means may have had to be protected against contact with the liquid adhesive material in the bath thereof during the dipping of the stator and winding means. Still another disadvantageous or undesirable feature of the past treatment method is believed to be that there may not have been sufficient distribution of the liquid adhesive material throughout the winding means and also between the interfaces of the laminations of the core, as were as an evenness of such distribution so as to deleteriously affect the strength of the core upon the bonding thereof.
In another of the past methods of treating the winding means of the above discussed past stator when the laminations thereof the were bonded together by a bolt-down bonding process, as previously mentioned and as taught for instance in U.S. Pat. No. Re. 26,788 issued Feb. 10, 1970 to Bobbie B. Hull which is incorporated herein by reference, only the opposite end turns of the coils were dipped in the bath of the liquid adhesive material prior to baking to effect the cure of the liquid adhesive material. Although this past method of treating the winding means of such past bolt-down bonded stator undoubtedly had many salient features, it is believed that such past method may have had at least some of the same disadvantageous or undesirable features as the previously discussed past treating method.
Another typical past stator of the loose wound type was formed with loosely stacked laminations having the stator slots thereof maintained generally in alignment by the slot liners disposed in the stator slots, and the winding means were associated with this loose lamination stack generally in the same manner as discussed hereinabove. One of the past treating methods for this loose wound stator or core involved mounting an aligning mandrel or the like for instance in the bore of the loose lamination stack, and thereafter baking, fully or completely dipping, and then rebaking the loose wound stator generally in the same manner as discussed hereinabove. Of course, in this instance, it is believed that for the most part, the liquid adhesive material may have flowed by capillary action from the outer circumferential surface of the stator between the interfacing laminations of the loose stack thereof so as to bond the laminations and the winding means together when the loose wound stator was rebaked to effect the curing of the liquid adhesive material; however, albeit not disclosed or even suggested by the known prior art, it is also believed that the possibility might have existed wherein some of the liquid adhesive material may have been transferred from the slots of the stator by capillary action between the interfacing laminations of the loose stack thereof. Nevertheless, it is believed that this past method of treating the loose wound stator had at least generally the same disadvantageous or undesirable features as the previously discussed past treating methods.
Still another past method of treating a loose wound stator or core involved the bolt down bonding process as shown in U.S. Pat. No. 3,821,846 issued July 2, 1974 to Bernard J. Pleiss, Jr. In this past method, a plurality of bolts are extended through bolt holes provided therefor in the loose lamination stack of the loose wound stator so as to mount an opposite end face thereof against a bolt-down fixture. Thus, upon torquing of the bolts, the laminations of the loose stack thereof were forced or clamped together by the bolts generally in the vicinity of the bolt hole thereby to establish generally axial compression regions generally adjacent the bolt holes between the opposite end faces of the loose wound stator. When so mounted to the bolt-down fixture, the loose wound stator was preheated and then dipped into the bath of the liquid adhesive material to a depth submersing the lamination stack but not one of the opposite end turn portions of the coils adjacent the lead ends thereof. Thus, the one opposite end turn portions of the coils adjacent the lead ends thereof were not dipped, but liquid adhesive material was later applied thereto. Since the bore of the loose wound stator was mounted on the alignment mandrel, as previously mentioned, it is believed that for the most part liquid adhesive material may have penetrated by capillary action from the outer circumferential surface of the lamination stack between the interfacing laminations thereof so as to cover the interfacing surfaces thereof without regard to the clamping of the bolts or the axial compression regions established thereby; however, albeit not discussed or even suggested in the Pleiss, Jr. patent, it is believed that the possibility may have existed wherein some of the liquid adhesive material may have been transferred from the slots of the stator by capillary action between the interfacing laminations of the stack thereof. Thereafter, the loose wound core mounted to the bolt-down fixture was transferred to a curing oven to be baked and effect the curing of the liquid adhesive material adhering to the lamination stack and the winding means which, as previously mentioned, served to bond them together. Nevertheless, it is believed that this past method of treating the loose wound core has at least generally the same disadvantageous or undesirable features as the previously discussed past treating methods.
In yet another past method of treating the winding means of the above discussed past stator core in which the laminations were fixedly interconnected together, such as by welding, bonding or cleating for instance, as previously mentioned, the stator core was rotated in only one direction with the bore of the stator extending generally horizontally. During the rotation of the stator in only the one direction, the liquid adhesive material was dripped or trickled onto the opposite end turn portions of the coils of the winding means associated with the stator and flowed therefrom generally along the opposite side turn portions of the coils into the stator slots in which the opposite side turn portions of the coils were received. However, one of the disadvantageous or undesirable features of this past treating method is believed to be that because the stator was rotated in only the one direction, some of the slots of the stator were starved, i.e., not adequately filled, with the liquid adhesive material flowed thereinto. For instance, due to the rotation of the stator in only the one direction, it is believed that a greater amount of the liquid adhesive material dripped onto the opposite end turn portions of the coils flowed therefrom generally along one of the opposite side turn portions of the coils into the stator slots in which the one opposite side turn portions of the coils were received while a lesser amount of the liquid adhesive material flowed generally along the other of the opposite side turn portions of the coils into the slots of the stator in which the other opposite side turn portions of the coils were received thereby, in effect, serving to starve such stator slots in which the other opposite side turn portions of the coils were received of an equal liquid adhesive material fill. In other words, due to the rotation of the stator in only the one direction, it is believed that the dripped liquid adhesive material had a gravitational tendency to flow "downhill" on the opposite end turn portions of the coils, i.e., in the direction of rotation of the stator, and then along the one opposite side turn portions of the coils into the stator slots receiving them, but the liquid adhesive material was at least inhibited with respect to flow "uphill" on the opposite end turn portions of the coils, i.e., against the rotation of the stator in only the one direction; therefore, the stator slots in which the other opposite side turn portions of the coils were received were generally starved of the liquid adhesive material, i.e., received the lesser amount of the liquid adhesive material dripped onto the opposite end turn portions of the coils in response to the rotation of the stator in only the one direction.